Reinforced multi-ply stay tape



y 14, 1963 H. HElSE EI'AL 3,089,634

REINFORCED MULTI-VPLY STAY TAPE Filed Sept. 27, 1961 3 Sheets-Sheet 1 1 V TORS How/71:0 5/55 65 1 20 o/v/Vfl L z. s' r52.

y 4, 1963 H. 1.. HEISE Em 3,089,634

REINFORCED MULTI-PLY STAY TAPE Filed Sept. 27, 1961 3 Sheets-Sheet 2 May 14, 1963 H. L. HEISE ETAL 3,

REINFORCED MULTI-PLY STAY TAPE Filed Sept. 27, 1961 3 Sheets-Sheet 3 INVENTORS. 1%n Ae0L/fE/sE. BYGOEDO/VM'AL L 15 T52 ATTORNEYS:

United States Patent O 3,089,634 REINFORCED MULTI-PLY STAY TAPE Howard L. Heise and Gordon McAllister, both of Troy, Ohio, assignors to St. Regis Paper Company, New York, N.Y., a corporation of New York Filed Sept. 27, 1961, Ser. No. 141,187 6 Claims. (Cl. 229-49) This invention relates to gummed tape and more particularly to so-called stay tape, which, among other possible purposes, may be used for forming corner joints of paperboard cartons.

More specifically the invention relates to the forming of an improved, inexpensive, multi-ply stay tape of kraft paper or other suitable sheet material and of exceptional strength and provided with longitudinally-extending strands for effectively reinforcing the tape in the sense that portions thereof may readily and quickly be stripped from a carton for easy opening of the container without causing portions of the tape to be transversely torn apart.

However, the use of any such reinforcing means, for example in the form of a strand or thread or the like adhered to the tape, has involved various difliculties. In the manufacture of tapes of the types here involved, it is customary to form the tape into disc-like rolls for shipment and later use on tape-applying mechanisms. To form such rolls, successive convolutions of the tape are wound flatwise in superposed relation and the rolls may for example be some six inches in diameter, or even as large as eighteen inches or more in diameter and contain hundreds of convolutions. But if the usual form of reinforcing strand is secured longitudinally along the midportion of such tape, then when the tape is wound into such rolls, the total thickness of the mid-portions of the numerous convolutions will be so much greater than the side portions, that the layers will not lie flat in firm contact throughout their width and as a result, successive convolutions of the roll will tend to slip or move more or less sideways with respect to each other, whereby the edges of some convolutions will extend out and be exposed at the face of the disc-like roll beyond others, and thus easily become frayed, creased or otherwise injured during shipment, and thus become unsuitable for use. In some cases the central portions of the roll may even slip so far out of place that the roll cannot be used on a taping machine. Also, if a single reinforcing strand is adhered along the mid-portion of such tape, then such strand in one convolution, upon tightly winding the roll, will tend to assume a position to one side of the strand on the next convolution, so that the edge of one convolution will necessarily be caused to extend out beyond the edge of the next. To avoid this, attempts have been made to apply a reinforcing strand to the tape along a varying path, instead of in a straight line, so that the strand in the next convolution cannot slip entirely to one side thereof or the other. But this will require that the strand of one convolution cross that of the next convolution from place to place, thereby, in any roll of substantial size, tending to increase the diameter of the central portions of the roll as compared with the edge portions, even more seriously than is caused by the presence of a single straight reinforcing strand.

The present invention provides a longitudinally reinforced tape construction which avoids these difliculties while having the requisite strength and flexibility, and this is accomplished by a construction in which the effective thickness of the tape construction, when wound into a roll, so nearly approximates a uniform thickness entirely across the width of the tape, despite the presence of reinforcing strands, that succeeding convolutions may be formed into a roll in which the convolutions are fairly "ice tightly super-imposed throughout their widths and with the edges remaining in alignment.

, Another problem with longitudinally-reinforced stay tapes has been that when the tape is secured to the cartons by tape applying machines, the positioning of the tape may vary or be inaccurate as compared with what is intended, so that the reinforcing strand at places will fall along a line spaced from the line along which the two adjacent wall panels meet, such as the line of the corner joint of the carton. As a result the reinforcing strand may become so firmly adhered to a wall panel of the carton, that when it is attempted to strip off the tape for easy opening of the carton, the reinforcing strand, and the tape as well, will be broken at places, or the tape will be irregularly torn or frayed, or small portions thereof and of the adjacent carton walls will be torn off so that the torn parts will present an unsightly and quite irregular appearance, which is particularly undesirable if the carton is to be used as a display case.

The present invention overcomes these difficulties in a way which does not detract from, but contributes to the provision of a substantially flat construction of such effectively uniform thickness that it can be tightly formed into a roll as above discussed.

In accordance with the present invention, a multi-ply tape construction of kraft paper or the like is provided preferably comprised of two layers of the paper, the side portions of which are adhered together while leaving the longitudinally extending mid-portions thereof not adhered together, but realtively flexible with respect to each other. And along the mid-portions of the face of the multi-ply tape which is to bear the glue to adhere same to a carton, a plurality of spaced-apart longitudinally extending reinforcing strands are adhered. These strands are preferably so formed as to be relatively flattened, and since they are applied along the region in under the longitudinally extending mid-portions of the construction which contain no glue between the plies, the absence of such glue makes it possible for the flattened strands to be sufliciently compacted against the paper so that the overall effective thickness of the two layers of paper, plus the strands along the mid-portion of the tape, will not be sufliciently greater than the overall thickness of the side portions of the tape to interfere with the forming of the tape into a tight roll and with the edges of the convolutions coterminous. At the same time, the use of a plurality of the reinforcing strands, sometimes two, but preferably three in the usual case, has the result that, even though the tape-applying machine may position the tape inaccurately, yet one or another, and possibly two of the strands, will extend along in the narrow gap or seam at which the carton walls are joined. Thus, when the tape is quickly pulled ofi, at least one or more of the strands will be readily pulled off since it will not be effectively glued to the carton wall surfaces, but will extend along the crevice between the edges thereof, such as at a corner joint.

Tape made in accordance with the invention as above Ibriefly described, has a further advantage that, due to the use of a plurality of spaced-apart reinforcing strands, the entire end portion of the taps may be grasped to permit stripping of a greater part of the entire width of the tape away from the carton, since the spaced-apart strands will reinforce a wide band of the tape against tearing. In using the invention in this way, the entire end of the tape as applied to the carton may provide a pull-tab, not adhered to the carton if there is printed on the carton an area, beneath the desired pull-tab portion, which blocks the action of the adhesive. Or if preferred, the ends of the tape as applied to the carton may be formed with short longitudinal slits at each side of the region bearing the reinforcing strands, thereby to provide a simple pulltab portion at the middle of the end of the tape, so that when this is pulled for opening the carton, the part of the tape which is stripped away from the corner joint of the carton is largely confined to the middle zone of the tape which bears the reinforcing strands and the torn-out strip is closely defined at its edges respectively by two of the strands, without leaving irregularly torn, unsightly or jagged edges on the opened carton.

Various further and more specific objects, features and advantages of the invention will appear from the description given below, taken in connection with the accompanying drawings, illustrating by way of example preferred forms of the invention.

In the drawings:

. FIG. 1 shows a roll of the multi-ply reinforcing tape made in accordance with the invention;

FIG. 2 is an enlarged perspective view of an end portion of a preferred form of the tape made in accordance with the invention;

FIG. 3 is an enlarged sectional view taken substantially along line 33 of FIG. 1 and showing cross-sections of a plurality of convolutions of the tape as wound into a roll and showing the manner in which one convolution lies fiat against preceding and succeeding convolutions;

'FIG. 4 is a greatly enlarged sectional view for showing particularly the end of one of the reinforcing strands as applied to one of the tape plies;

FIG. 5 is a perspective view of a so-called end loading type of carton having a corner closure formed of tape in accordance with the invention and showing one manner in which such tape may be stripped away for easy opening of the carton;

'FIG. 6 is a perspective view of another carton illustrating a somewhat different embodiment of the tape as usde for forming the carton corner joint;

FIG. 7 is an enlarged cross-sectional view showing a corner of a corrugated paperboard box secured by the tape construction in accordance with the invention;

FIG. 8 is a perspective view of an end portion of a piece of the tape of the type used for the construction shown in FIG. 6; and

FIG. 9 is a schematic view illustrating arrangements which may be used for forming tape in accordance with the invention.

Referring now to the drawings in further detail, as shown in FIGS. 1 and 2, the tape construction may comprise an outer paper ply as at 10 (shown on the underside in these figures) and an under paper ply, as indicated at 11, the facing marginal regions along the edges of these plies being adhered together by adhesive as indicated at 12, the adhesive used being of any suitable known type, preferably a thermoplastic adhesive insoluble in water such as polyamide or polyvinyl acetate adhesives, although water-activated adhesives may be used. While this adhesive layer may have some substantial thickness, it will be understood that in the drawings for clearness it is shown of a somewhat exaggerated thickness.

Along a band of considerable width at the mid-portions of the multi-ply tape, the facing surfaces thereof are left free of adhesive and initially and normally the plies 10 and 11 at this region will be spaced apart somewhat, as indicated at 13, and relatively flexible with respect to each other. The surface of the ply 11 which is to be adhered to a carton or other surface on which the tape is to be used, is entirely covered with a coating of glue or other adhesive 14 of a suitable type such as used for gummed stay tape. After such adhesive coating has been applied and becomes dry, it may tend to shrink the paper ply 11 somewhat so that its width will be less than the width of the ply 10, even though the plies as initially made were of the same width. Such shrinkage will tend to cause the mid-portions of the ply 10 to bulge somewhat away from the mid-portions of the ply 11, leaving a noticeable space as at 13 therebetween.

A plurality of parallel, longitudinally-extending, reinforcing strands, for example two, but preferably three as indicated at 15, 16 and 17, are adhered at spacedapart positions to the ply 11 by the adhesive or glue 14. Each of these strands preferably is comprised of a continuous length of viscose rayon yarn having a very small, or preferably a zero twist, and composed of a multitude of fine filaments. In order to prevent this yarn from readily fraying and to retain the filaments thereof in the desired position, a suitable dressing is preferably applied just before the strands are applied and adhered to the paper ply 11. This dressing may, for example, comprise a dilute styrene-butadiene copolymer latex having a high flexibility when dry, or other materials such as copolymers of vinyl acetate or vinyl chloride might be used for the purpose. The amount of such dressing applied may be readily determined by trial, depending upon the nature and dimensions of the particular strands used, but care should be taken not to apply any such excess of the dressing as may cause the strands to lose their high degree of resiliency or to break when the tear strip is drawn back upon itself at a sharp angle while stripping it from a carton to open the carton. A moderate amount of the dressing will be sufiicient to prevent the strands from becoming too easily frayed. The strands are applied in straightened condition and under some slight pressure against the glue surface 14 and While the dressing of the strands is still somewhat fluid. The tape construction is then passesd over suitable rollers through a dryer, with the result that the strands being either untwisted or having a very low twist, will be free to assume a preferred generally flattened condition, as best shown in FIG. 4, with a surface coating of the dressing thereon as indicated at 18, the filaments in FIG. 4 being indicated at 19. When the construction as shown in FIG. 2 is wound into a roll as shown at 20 in FIG. 1 for example, the superimposed convolutions will lie generally fiatwise of each other and under pressure against each other along their side portions as well as along their mid-portions where the strands are located. If one presses against the periphery of the completed roll, either at the marginal or central portions of the tape, the roll will be found to be firm and compact. Also, under these circumstances, the edges of the tape will accurately coincide, so that the faces of the disc-like roll will conform to flat planes.

Referring more specifically to FIG. 3, it will be noted that the space between the mid-portions of the plies 10 and 11 Will become collapsed at the regions where the strands are located and that the opposed surfaces of the plies at these regions will therefore come into firm contact, as indicated at 21. There being no space required for glue or adhesive between the plies at this region, and the paper of the plies remaining relatively soft and flexible in the absence of adhesive, it becomes possible for the overall thickness of the tape, including the strands at this region, to be not substantially greater than the overall thickness of the tape along the marginal portions where the tapes are secured together by adhesive 12. On the other hand, if the paper plies were adhered together by glue or other adhesive throughout their widths, then of necessity the tape would be relatively firm or hard and of uniform thickness throughout its width, apart from the presence of the strands and with the strands added, the overall thickness at the middle region would be increased so as to be great enough to cause the difficulties in forming useful rolls thereof as hereinabove explained. However, this difficulty with the present invention is avoided by taking advantage of the fact that no space is required for gluing the plies together at the mid-portions and the fact that the mid-portions are in a relatively soft condition free of hardened adhesive when the strands are applied, and thus the strands may press somewhat into the paper, and whether or not the strands are relatively flattened as preferred, the convolutions of a roll of the tape will be so nearly uniform in overall thickness that they will lie fiat and in firm contact at the margins as well as the mid-portions of the width of the tape.

The U.S. patent to Bruce et al. No. 2,651,588 discloses a multi-layer stay tape formed for example of two or more strips of kraft paper with the contacting surfaces thereof adhered together along the regions of their margins While leaving the contacting surfaces of the plies free of adhesive along the mid-portions of the tape and thus the mid-portions remain more flexible, and being multi-ply, same are effectively stronger and less likely to crack or tear in use, when applied for example to a box corner, than if the plies were adhered throughout their contacting surfaces. The present invention makes it possible to take full advantage of the improved strength and flexibility characteristics of the invention of that patent, while combining .and augmenting such advantages with those afforded by the use of the particular form of longitudinal reinforcing strands so constructed and applied that the tape may as a result readily be made into stable rolls thereof. That is, the adhesive-free surfaces within the mid-portion of the tape provide cushioning areas against Which the strands of appropriate limited cross-section may be so applied as to atford that result, and yet be longitudinally reinforced so adequately that the tape or portions thereof may be quickly stripped from a carton for easy opening without disruption of the tape transversely and without leaving unsightly torn or rough areas on the container.

In a typical construction in accordance with the invent-ion, tape adapted for use in forming the corner joint on corrugated paperboard shipping cartons for example, may have the following specifications: the width of the tape may be approximately 2 inches; the mid-portion thereof where the plies are not adhered together may, for example, be about one-third of the total tape width; the plies may be formed of kraft paper having a kraft paper basis weight of 78 lbs. (equivalent to so-called linerboard basis weight of 26 lbs.). These basis weights, of course, may vary for example as much as seventy (70) percent in either direction, depending upon the particular use intended for the tape and of course the width thereof may also vary widely. In a typical case, each of the reinforcing strands, in the form of 1650 denier viscose rayon (although this figure may vary in either direction by some 70% or more) may contain some hundreds of fine filaments, and as above indicated, the strands preferably have zero twist. Although strands of rayon are preferred, other materials may be used such as nylon, which although stronger in this situation may tend to fray excessively even after aplication of the dressing. While glass fiber may be used, it will have a greater tendency to break when the tape is stripped off by pulling same at a sharp angle. Cotton strands of appropriate size tend generally to be too weak, although same might under some circumstances be used. In a typical example, the width of that portion of the tape occupied by the strands may vary from three-sixteenths to five-sixteenths inch. If the strands are relatively closely spaced, this will insure that the entire space or crevice to which the tape is applied along a box corner, for example, will be protected against injury of the paper of the tape by reason of the presence of the strands which will resist being cut by the contents of the carton, for instance in case the carton contains objects such as cans. That is, the abruptlyshaped chimes on the cans will not cause disruption of the reinforcing strands, even if the joint is opened somewhat after repeated blows against the box, or after the shape of the box begins to deteriorate.

FIG. 5 illustrates the manner in which tape in accordance with the invention may be applied to form the corner point of a paperboard carton 29 such as of the so-cal-led end-loading type. Here the tape has been so applied as to be adhered astride the corner 30 of the carton which has been loaded through an end as at 311 thereof. Before application of the tape in this form, printed adhesive-blocking areas, as at 32, are provided by the use of suitable known adhesive-blocking material of a greasy nature or otherwise, which will prevent the end portion of the tape as at 34 from being adhered so as to leave this portion free as a pull-tab. Thus when this portion is grasped, as indicated, and quickly drawn back, the entire tape may be removed from the corner areas of the carton, leaving the carton free to be opened (so far as concerns this corner). In this case the middle regions of the tape bearing the reinforcement strands will generally be wide enough and strong enough to enable the entire tape to be pulled free of the carton without leaving any particularly unsightly torn areas and without tearing the tape transversely.

With the invention shown in FIG. 6, the tape is applied to form the vertical joint at the corner of a carton 36. Here an end portion of the tape, as indicated in FIG. 8,

may be slit as at 37 and 3S tor a short distance inwardly of the end of the tape and along opposite sides of the regions thereof which bears the reinforcing strands. This makes possible the provision of a pull-tab portion 40 which may be grasped by the fingers and pulled down quickly and abruptly, thereby to tear from the tape a strip of the mid-portion thereof, which strip will be fairly closely defined at its edges respectively by the two strands 15 and 17 without leaving irregularly torn or jagged edges on the opened carton.

FIG. 7 is a cross-sectional view through a corner joint made by the use of tape in accordance with the invention, and where two wall panel portions, as at 41, 42,, of corrugated paperboard for example, are secured together along their contiguous edges at a corner 43. In the particular instance here shown by way of example, it will be noted that the tape was applied as for instance by an automatic taping machine in a slightly off-center position with respect to the corner, that is, in a position such that while strands 16 and 17 are so positioned as to extend along and face the space or crevice 44 at the corner, yet strand 15 is adhered along on the panel 41 near the edge thereof. In some cases, the tape may be so applied that two of the strands will be adhered to the edges of one or another of the panels, leaving only one strand facing the corner space, yet in any case when the customary tape-applying means are used, it will be applied at the desired location with sufiicient accuracy so that at least one of the strands will be located within the corner space or crevice and thus will be free, without any adhesive binding, to be stripped from the corner and hence it will ordinarily lend suflicient strength to insure that the adjacent portions of the tape also will be stripped 'from the corner without difficulty. We may here revert to FIG. 2 and note that, while as shown, the middle portion of the paper ply '10 bulges away from the ply 1L1, yet when the tape is wound in a roll with the convolutions as indicated in FIG. 3, the space 13 between the two plies will have become collapsed and then again when the tape is unrolled, the space '13 may again appear, but when the tape is applied astride a box corner as shown in FIG. 7, the mid-portion of the outer ply where it curves around the corner, will again snugly come into contact with the mid-portion of the under ply 11 as shown.

FIG. 9' illustrates one possible example of an arrangement for manufacturing the tape in accordance with the invent-ion. As here shown, rolls of paper which are to form the two plies respectively are indicated at 45 and 46. The paper may be drawn from the roll 46, past glue applicator means as at 4'7 for applying spaced bands of adhesive thereto, that is, adhesive which is to be embedded in the marginal portions of the tape, as indicated at 12 in FIG. 3. It will be understood that, with the equipment shown in FIG. 9, the paper used may be wide enough to total the width of many strips of tape, and after same has gone through the apparatus, the product may be longitudinally cut into the numerous desired tapes. The two bands of paper from the rolls of paper '45 and 46 become superapaaesa posed on a roll as at 48 and thence may be passed over a heated dryer roll for drying the adhesive applied at 47. Thence the two-ply material may pass over suitable rollers and through a drying chamber as at 51. Thereafter the two-ply material is led over a glue applicator means as at 5 2 for applying glue throughout the surface areas of the material which are to be adhered to hold the tape in position when used. Rolls of the strand material are indicated at 53, 54, 55, from which the strand material is led through suitable pan means as at 56 for applying the dressing material thereto, and the strands as thus treated, are then led onto the glue-bearing surface of the multiply paper at roller 57. Thence the material passes through drying means as at 58 to a take-up roll 59, or the material may be cut into tapes of the desired width be fore being wound.

Although certain particular embodiments of the invention are herein disclosed for purposes of explanation, further modifications thereof, after study of this specification, will be apparent to those skilled in the art to which the invention pertains. Reference should accordingly be had to the appended claims in determining the scope of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. Multiply stay tape comprising at least two superposed strips of flexible sheet material, the marginal portions of the surfaces thereof which face each other being secured together by longitudinally extending bands of adhesive, the mid-portions of the surfaces thereof which face each other and are located between said bands being free of adhesive and free directly to contact each other, the surface of one of said strips which is adapted to be secured to an object when the tape is in use, being covered with an activatable adhesive and said latter surface having adhesively secured thereto along its mid-portions at least one longitudinally extending reinforcing strand formed of a multitude of fine filaments secured by adhesive to each other against fraying, said strand being of such limited cross-section and the adhesive-free portions within the tape providing a cushioning zone for the strand such that the tape may be wound into a roll with a multitude of convolutions which lie in firm relationship throughout their width and with substantially the same diameters at their marginal portions as at their mid-portions.

2. A roll of stay tape comprising a multitude of superposed convolutions of multi-ply tape constructed in accordance with the foregoing claim 1, the edges of such convolut-ions being co-extensive and the superposed convolutions lying under pressure against each other in firm relationship throughout and with substantially the same diameters at their marginal portions as at their midportions.

3. A paperboard carton having a corner joint comprised of stay tape constructed in accordance with the foregoing claim 1, said tape being adhered along astride the crevice region at the corner of the carton, the midportions along within the tape which are free of adhesive extending along and covering said crevice and said strand being on the interior surface of the tape and extending along within such crevice.

4. Multi-ply stay tape constructed in accordance with the foregoing claim 1 and in which the adhesive-free surfaces on the mid-portions of the superposed strips of material within the tape are normally somewhat bulged to spaced apart relation when the tape is free of pressure, but free to come into contact with each other when pressure is applied to the tape.

5. Multiply stay tape comprising at least two superposed strips of flexible sheet material, the marginal portions of the surfaces thereof which face each other being secured together by longitudinally extending bands of adhesive, the mid-portions of the surfaces thereof which face each other and are located between said bands being free of adhesive and free directly to contact each other and to flex with respect to each other, the surface of one of said strips which is adapted to be secured to an object when the tape is in use, being covered with an activat-able adhesive and said latter surface having adhesively secured thereto along its mid-portions a plurality of longitudinally extending substantially parallel and spaced-apart reinforcing strands, each of which is substantially twist-free and is formed of filaments secured by adhesive to each other against fraying, said strands being of such limited cross-section and the adhesive-free portions within the tape providing a cushioning zone for the strands such that the tape may be wound into a roll with a multitude of convolutions which 'lie in firm relationship throughout their width and with substantially the same diameters at their marginal portions as at their mid-portions.

6. A paperboard carton having a corner joint comprised of stay tape adhered along astride the corner and constructed in accordance with the foregoing claim 5 and with said plurality of strands extending along on the sur- [face of the tape which is adhered to the carton and with at least one of said strands extending along within the crevice of the corner joint, and all said strands being covered by said mid-portions where the surfaces of the strips of sheet material which face each other are free of adhesive.

References Cited in the file of this patent UNITED STATES PATENTS fn mms-nn. 

1. MULTI-PLY STAY TAPE COMPRISING AT LEAST TWO SUPERPOSED STRIPS OF FLEXIBLE SHEET MATERIAL, THE MARGINAL PORTIONS OF THE SURFACES THEREOF WHICH FACE EACH OTHER BEING SECURED TOGETHER BY LONGITUDINALLY EXTENDING BANDS OF ADHESIVE, THE MID-PORTIONS OF THE SURFACE THEREOF WHICH FACE EACH OTHER AND ARE LOCATED BETWEEN SAID BANDS BEING FREE OF ADHESIVE AND FREE DIRECTLY TO CONTACT EACH OTHER, THE SURFACE OF ONE OF SAID STRIPS WHICH IS ADAPTED TO BE SECURED TO AN OBJECT WHEN THE TAPE IS IN USE, BEING COVERED WITH AN ACTIVATABLE ADHESIVE AND SAID LATTER SURFACE HAVING ADHESIVELY SECURED THERETO ALONG ITS MID-PORTIONS AT LEAST ONE LONGITUDINALLY EXTENDING REINFORCING STRAND FORMED OF A MULTITUDE OF FINE FILAMENTS SECURED BY ADHESIVE TO EACH OTHER AGAINST FRAYING, SAID STRAND BEING OF SUCH LIMITED CROSS-SECTION AND THE ADHESIVE-FREE PORTIONS WITHIN THE TAPE PROVIDING A CUSHIONING ZONE FOR THE STRAND SUCH THAT THE TAPE MAY BE WOUND INTO A ROLL WITH A MULTITUDE OF CONVOLUTIONS WHICH LIE IN FIRM RELATIONSHIP THROUGHOUT THEIR WIDTH AND WITH SUBSTANTIALLY THE SAME DIAMETERS AT THEIR MARGINAL PORTIONS AS AT THEIR MID-PORTIONS. 